The impact of the fabrication method on the three-dimensional accuracy of an implant surgery template

The Impact of Three-Dimensional Printer Technology on the Accuracy of Dental Implant Models

This study examines the impact of different 3D printing technologies on the accuracy of implant positions in printed dental models, a crucial factor in implant-supported prosthetics. A standardized titanium model with three bone-level implants was scanned using an industrial scanner to create a virtual reference model. Ten intraoral scans of the same model were performed, and the generated STL files were used to design physical models printed with three different 3D printers: two utilizing digital light processing (DLP) technology and one employing stereolithography (SLA) (n = 30). The printed models were then rescanned, and deviations from the reference STL file were analyzed. Results showed that the SLA printer exhibited the highest deviations (0.26 ± 0.17 mm), whereas the DLP printers demonstrated greater accuracy, with one DLP system (0.07 ± 0.02 mm) performing slightly better than the other (0.12 ± 0.13 mm). The SLA printer exhibited the most significant errors in the vestibulo-oral and occlusal-apical directions. The findings suggest that DLP printers offer superior precision for implant-supported restorations in digital workflows. Clinically, the choice of 3D printing technology significantly impacts model accuracy, emphasizing the importance of selecting the appropriate printer based on the required precision.

Accuracy of Three-Dimensional Computer-Aided Implant Surgical Guides: A Prospective In Vivo Study of the Impact of Template Design

Background: Digital planning and the use of a static surgical guide for implant placement provide predictability and safety for patients and practitioners. The aim of this study was to investigate differences in the accuracy and fit of long and short guides. Methods: In patients with at least one missing tooth, long (supported by the entire dental arch) and short templates (supported by two teeth, mesial and distal) were compared via intraoral scans and the superimposition of the STL files of the initial planning and the actual position in the patient's mouth along the X-, Y- and Z-axes. Furthermore, this study evaluated the conditions (e.g., mouth opening, the implant position) under which fully guided implantation can be realized. Results: The largest deviation was observed in the Z-axis, although this deviation was not as high for the short templates (0.2275 mm) as it was for the long templates (0.4007 mm). With respect to the 3D deviation (dXYZ), the average deviation from the mean value was 0.2953 mm for the short guides and 0.4360 mm for the long guides (p = 0.002). The effect size (Cohen's d) was 0.709, which was between the medium (0.50) and large effect sizes (0.80). The shorter templates showed a smaller deviation from the actual plan by 80%. With a mouth opening ≥50 mm, fully guided surgery can be performed in the molar region. In the premolar region, the lower limit was 32 mm. Conclusions: The 3D accuracy was significantly higher for the shorter template, which could therefore be favored.

Prospective Clinical Study on the Accuracy of Static Computer-Assisted Implant Surgery in Patients With Distal Free-End Implants. Conventional Versus CAD-CAM Surgical Guides

OBJECTIVES

To compare the accuracy of CAD-CAM and conventional guides in the static computer-assisted implant surgery (sCAIS) placement of distal free-end implants.

MATERIAL AND METHODS

A prospective, controlled, and blinded quasi-experimental study was done involving 27 patients (76 implants) distributed into two groups according to the surgical guide manufacturing approach used: conventional (control group [CG]) or CAD-CAM (test group [TG]). The implants were planned in the software and the surgical guides were manufactured. Fully guided implant placement was carried out and the deviations were measured along with secondary variables as potential confounding factors. Descriptive analyses were performed on mean, standard deviation (SD), and interquartile range (IQR). In the comparative/inferential analysis hypothesis, contrasts were made of the quantitative and qualitative variables and multiple linear models were generated to adjust for the different confounding variables recorded.

RESULTS

Coronal horizontal deviation (CHD) was significantly greater in CG (1.52 mm) versus TG (1.04 mm) (p = 0.004). Apical horizontal deviation (AHD) in turn was 1.67 versus 1.46 mm, respectively; angular deviation was 2.87 versus 3.64; and vertical deviation was -0.1 versus -0.05 mm, with no significant differences between the groups (p > 0.05). A greater sleeve height, positioning in premolars versus molars, and the use of shorter implants, were associated with greater accuracy in relation to CHD and/or AHD (p < 0.05). The implant success rate at 1 year was 92.1%, 90.7% in TG, and 100% in CG, being statistically significant (p = 0.026) at the implant level, but not significant at the patient level.

CONCLUSIONS

The CAD-CAM surgical guides proved to be more accurate than the conventional guides in the sCAIS placement of distal free-end implants, with statistically significant differences being observed in terms of CHD. All implant failures occurred in TG (6 implants/3 patients).

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT06404385.

Influence of two different printing methods on the accuracy of full-guided implant insertion - a laboratory study in undergraduate dental students

OBJECTIVES

The aim of the present study was to compare the accuracy of fully guided implant insertion in vitro achieved by two fabrication methods in a cohort of undergraduates. We hypothesized that both methods achieve a comparable accuracy.

METHODS

Surface scans and cone beam computed tomography images of 48 mandibular models were matched. For each model, two surgical guides enabling a fully guided implant insertion in the region of the first molar on the left or the right side were virtually designed. Fabrication by either Digital Light Processing (DLP) or Fused Filament Fabrication (FFF) followed. Subsequently, 96 implants using the guides were inserted into the models by 48 undergraduate students. The accuracy of the implant insertion was assessed radiographically, followed by statistical analysis. Additionally, all participants completed a questionnaire.

RESULTS

The implants inserted using guides made by DLP showed a higher accuracy compared to guides made by FFF. The mean three-dimensional deviation was 1.94 ± 1.05 vs. 3.35 ± 2.03 degrees (p < 0.001). The evaluation of the questionnaires revealed mainly theoretical knowledge and a pronounced interest in implant dentistry.

DISCUSSION

The main hypothesis has to be rejected as there were statistically significant differences in accuracy. However, it is possible to teach students the principles of guided implant dentistry and the digital workflow. Furthermore, the initial and running costs for the FFF workflow are substantially lower enabling a higher practicability for undergraduate education.

CONCLUSION

Despite the lower accuracy of the templates made from FFF the method seems to be suitable for laboratory hands-on courses for undergraduates.

Accuracy of full-guided versus half-guided implant procedures carried out with digital implant planning software by students as part of a university curriculum

BACKGROUND

This in vitro study investigated whether full-guided (FG) or half-guided (HG) implant placement is more suitable for beginners and to what extent the use of the coDiagnostiX (CDX) (10.5, Straumann Group, Basel, Switzerland) implant planning software proves useful in teaching.

METHODS

Twenty students planned implant positions with CDX which were then placed in a model using printed drill templates in the sense of FG implantation (group 1) and HG implantation (group 2). The implant positions could be compared with those of the reference model, and deviations could be determined. The results were tested for significance using the t-test for independent samples for groups 1 and 2. A total of 32 students subsequently completed a questionnaire about the software. Cronbach's α was also calculated to check the reliability of the questions for the individual subject areas.

RESULTS

In both groups the greatest deviation occurred along the y-axis in the vestibular direction. It measured 1.390 mm in group 1 and 1.570 mm in group 2. Comparing both groups, there were significant deviations along the y-axis (p = .013), along the z-axis (p = .049), and in the total deviation (p = .031). The questionnaire was evaluated in design, with 95% positive answers. In contrast, the evaluation of the area of time and effort resulted in only 55% positive responses. Overall, experience with the software was rated as positive by 74%.

CONCLUSIONS

Group 1 achieved more accurate results, especially along the y-axis in the vestibular direction. In both groups, the implants were placed too deep. The questionnaire indicated a software with high usability and is therefore very suitable for teaching. If clinically feasible, beginners should prefer full-guided implant placement.

Digitization of Dentate and Edentulous Maxillectomy and Mandibulectomy Defects with Three Different Intraoral Scanners: A Comparative In Vitro Study

Objectives: The objective of this study was to compare the trueness and precision of three intraoral scanners (IOSs) for the digitization of dentate and edentulous maxillectomy and mandibulectomy defects in artificial models. Methods: Four representative defect models-a dentate and an edentulous maxillectomy model and a dentate and an edentulous mandibulectomy model-were used for digital scanning. After a reference scan of each model, they were scanned with three IOSs: CEREC AC Omnicam, True Definition, and cara TRIOS 3. For comparison, five conventional impressions with a polysiloxane material were taken and digitized with a laboratory scanner. The obtained data were evaluated with three-dimensional (3D) inspection software and superimposed with the reference scan data by using a best-fit algorithm. The mean absolute 3D deviations of the IOS compared to the reference data (trueness) and when comparing the datasets within the IOS (precision) were analyzed. Linear mixed models and multiple pairwise comparisons were used for statistical analyses. Results: The overall comparison of the four evaluated procedures for data acquisition showed a significant difference in trueness (p < 0.0001) and precision (p < 0.0001). The average mean trueness of the IOSs ranged from 32.17 to 204.43 µm, compared to 32.07 to 64.85 µm for conventional impressions. Here, the conventional impression and cara TRIOS 3 performed the most precisely with no significant difference. CEREC AC Omnicam achieved the worst precision. Conclusions: Using a suitable intraoral scanner, defective jaws even without teeth could be captured in satisfying accuracy. This shows the possibility to use an intraoral scanner for maxillofacial defect patients and gives a vision of using digital technology in maxillofacial prosthetics.

Achieving automated and high-precision in situ analysis of the dimensional accuracy and dynamic deformation of 3D-printed surgical templates: an in vitro study

PURPOSE

To demonstrate the viability of a coordinate-measuring machine (CMM) for the geometric analysis of 3D printed surgical templates.

METHODS

The template was designed and modified by adding 18 cylindrical landmarks for CMM test and then classified into five groups according to the slicing software and resins (opaque and transparent): Streamflow-O, Streamflow-T, Shapeware-T, Rayware-T and Polydevs-T (N = 3). Three standing times (0 w, 1 w, and 2 w) were included to observe possible deformation. All the measurements were performed automatically by the CMM through a preset program. The Euclidian distance (dxyz) was regarded as the representation of global dimension accuracy, and displacements in the x-, y-, and z-axes were also calculated.

RESULTS

The average dxyz values of Streamflow-O, Streamflow-T, Shapeware-T, Rayware-T and Polydev-T are 32.6 μm, 31.3 μm, 56.4 μm, 96.4 μm, and 55.3 μm, respectively. Deviations were mainly induced by the upward bending of the free end region (positive direction of the z-axis). Different resins did not have a significant influence on the dimensional accuracy. Moreover, deformation appeared to be negligible after 2 weeks of storage, and the z-axis displacements were only approximately 30 μm at week 1 and 10 μm at week 2.

CONCLUSIONS

The deviations of the DLP-printed template are induced mainly by z-axis displacements and are determined by the processing accuracy. After 2 weeks, the dimensional stabilities of these templates are reliable, which is encouraging for clinicians. Moreover, the CMM is preliminarily demonstrated to be a feasible tool for achieving automated geometric analysis of surgical templates.

Digital Surgical Guides in Mandibular Genioplasty: Evaluating Precision Against Conventional Techniques

BACKGROUND

Mandibular genioplasty, a central procedure in oral and maxillofacial surgery, has traditionally relied on surgeon experience with potential limitations in precision. The advent of digital methods, particularly computer-aided design/computer-aided manufacturing (CAD/CAM), offers a promising alternative. This study aims to evaluate the efficacy of digital surgical guides in improving the precision of mandibular genioplasty.

METHODS

A prospective analysis of 50 patients undergoing genioplasty was performed, 30 in the experimental group using digital surgical guides and 20 in the control group using traditional methods. Three-dimensional reconstructions were obtained using cone-beam computed tomography (CBCT) and digital scans. Osteotomy guides were 3D-printed based on group assignment. Postoperatively, accuracy was assessed by measuring distances between landmarks.

RESULTS

The experimental group showed significantly reduced horizontal positioning errors in genioplasty advancement, with no significant differences in vertical errors. For genioplasty retraction, the experimental group showed fewer vertical positioning errors, while horizontal errors remained consistent.

CONCLUSIONS

The use of digital surgical guides in mandibular genioplasty significantly improves surgical accuracy, resulting in improved outcomes and patient satisfaction. This study highlights the potential of digital methods in refining oral and maxillofacial surgical procedures.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Current applications of 3D printing in dental implantology: A scoping review mapping the evidence

OBJECTIVES

This scoping review aimed to identify the available evidence in the use of 3D printing technology in dental implantology. Due to the broad scope of the subject and its application in implantology, three main areas of focus were identified: (1) customized dental implants, (2) manufacturing workflow for surgical implant guides, and (3) related implant-supported prostheses factors, which include the metallic primary frameworks, secondary ceramic or polymer superstructures, and 3D implant analog models.

MATERIALS AND METHODS

Online databases (Medline, Cochrane, Embase, and CINAHL) were used to identify the studies published up to February 2023 in English. Two experienced reviewers performed independently the screening and selection among the 1737 studies identified. The articles evaluated the additive manufacturing (AM) technology, materials, printing, and post-processing parameters regarding dental implantology.

RESULTS

The 132 full-text studies that met the inclusion criteria were examined. Thirteen studies of customized dental implants, 22 studies about the workflow for surgical implant guides, and 30 studies of related implant-supported prostheses factors were included.

CONCLUSIONS

(1) The clinical evidence about AM titanium and zirconia implants is scarce. Early data on survival rates, osseointegration, and mechanical properties are being reported. (2) 3D printing is a proven manufacturing technology to produce surgical implant guides. Adherence to the manufacturer's instructions is crucial and the best accuracy was achieved using MultiJet printer. (3) The quality of 3D printed prosthetic structures and superstructures is improving remarkably, especially on metallic alloys. However, better marginal fit and mechanical properties can be achieved with milling technology for metals and ceramics.

Impact of Scanbody Geometry and CAD Software on Determining 3D Implant Position

The implementation of CAD software in the digital production of implant prosthetics stands as a pivotal aspect of clinical dentistry, necessitating high precision in the alignment of implant scanbodies. This study investigates the influence of scanbody geometry and the method of superimposing in CAD software when determining 3D implant position. A standardized titanium model with three bone-level implants was digitized to create reference STL files, and 10 intraoral scans were performed on Medentika and NT-Trading scanbodies. To determine implant position, the generated STL files were imported into the Exocad CAD software and superimposed-automatically and manually-with the scanbody geometries stored within the software's shape library. Position accuracy was determined by a comparison of the 3D-defined scanbody points from the STL matching files with those from the reference STL files. The R statistical software was used for the evaluation of the data. In addition, mixed linear models and a significance level of 0.05 were applied to calculate the p-values. The manual overlay method was significantly more accurate than the automatic overlays for both scanbody types. The Medentika scanbodies showed slightly superior precision compared to the NT-Trading scanbodies. Both scanbody geometry and the type of alignment in the CAD software significantly affect digital workflow accuracy. Manual verification and adjustment of the automatic alignment process are essential for precise implant positioning.

Influence of surgeon experience on implant placement in guided surgeries: A systematic review and meta-analysis of randomized clinical trials

STATEMENT OF PROBLEM

Guided surgical techniques in implant dentistry use virtual planning to accurately position implants. Understanding the effect of a surgeon's experience on guided surgery is essential to ensure successful outcomes.

PURPOSE

The purpose of this systematic review and meta-analysis of randomized clinical trials was to evaluate the influence of a surgeon's experience on the accuracy of implant positioning in guided surgery for completely or partially edentulous patients.

MATERIAL AND METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, searches were conducted in the PubMed, Scopus, Web of Science, EMBASE, Cochrane Library, SciELO, and nonpeer-reviewed literature databases. Studies that met the population, intervention, control, and outcome (PICO) strategy were included: a completely or partially edentulous maxilla or mandible, guided surgery performed by experienced and inexperienced surgeons, and assessing implant positioning accuracy. A random-effects meta-analysis with a 95% confidence interval was conducted using Stata 15.1. The risk of bias was assessed with the Cochrane risk-of-bias tool for randomized trials (RoB2), and evidence certainty was evaluated using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) tool. The study was registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42022302288).

RESULTS

Three articles from 2017 to 2020 encompassing 43 participants (22 men and 21 women) with a mean age of 61.2 years and a total of 150 implants were included. No significant difference was found between experienced and inexperienced surgeons in terms of angular, cervical, or apical deviations of the implants (95% confidence interval, P<.05). The difference between surgeons regarding positioning accuracy was less than 0.01 degrees for angular deviation, 0.35 mm for apical deviation, and 0.16 mm for cervical deviation. Low heterogeneity was observed for angular deviations (Q P=.021, I2=34%, and t2<.001) and cervical deviations (Q P=.18, I2=45%, and t2=.064). High heterogeneity was observed for apical deviations (Q P<.001, I2=87% and t2=.522). The overall bias risk was moderate, with the evidence certainty ranging from low to moderate.

CONCLUSIONS

In guided surgery, the surgeon's experience did not significantly impact the occurrence of deviations in implant positioning.

The Utility of 3D Printing for Surgical Planning and Patient-Specific Implant Design in Maxillofacial Surgery: A Narrative Review

Maxillofacial reconstructive implants are typically created in standard shapes and have a widespread application in head and neck surgery. During surgical procedures, the implant must be correctly bent according to the architecture of the particular bones. Bending takes practice, especially for untrained surgeons. Furthermore, repeated bending may increase internal stress, resulting in fatigue in vivo under masticatory loading and an array of consequences, including implant failure. There is a risk of fracture, screw loosening, and bone resorption. Resorption, infection, and displacement are usually associated with the use of premade alloplastic implants and autogenous grafts. Recent technological breakthroughs have led to the use of patient-specific implants (PSIs) developed by computer-designed additive manufacturing in reconstructive surgery. The use of computer-designed three-dimensional (3D)-printed PSI allows for more precise restoration of maxillofacial deformities, avoiding the common difficulties associated with premade implants and increasing patient satisfaction. Additive manufacturing is something that refers to a group of additive manufacturing methods. This technique has been quickly used in a variety of surgical procedures. The exponential expansion of this technology can be attributed to its enormous surgical value. Adding 3D printing to a medical practice can be a rewarding experience with stunning results.

Influence of the Printing Orientation on Parallelism, Distance, and Wall Thickness of Adjacent Cylinders of 3D-Printed Surgical Guides

This in-vitro study aimed to evaluate the influence of the printing orientation on parallelism, distance, and thickness between adjacent cylinders of 3D-printed surgical guides. CAD software was used to design a surgical guide with two adjacent parallel cylinders (reference); the design was saved as standard tessellation software (STL) and 63 samples were printed using three different orientations (0, 45, and 90 degrees). A metrology digital microscope was used to measure the distance, the angle and the thickness of the guides cylinders. Afterwards, the printed guides were scanned and cloud comparison software was used to compare STL files from the printed guides against the reference CAD model. One-way analysis of variance and Tukey test were used for multiple comparisons between groups and significance was p < 0.05. The printing orientation affected the distance between cylinders, the parallelism and the wall thickness. In addition, there were global deviations in all printing orientations. Printing with 90 degrees orientation produced almost-parallel cylinders but walls thicker than the reference model; all the cylinders converged toward the coronal but printing at 0 degrees produced the closest distance to the reference value. Within the limitations of this experimental in-vitro study it can be concluded that all the printing orientations influence the angle, the distance, and the thickness between adjacent cylinders of a surgical guide. Printing at 90 degrees produces the best global correspondence with the master model.

Accuracy of full-guided vs. pilot-guided implant insertion - A prospective laboratory study in fifth-year dental students

BACKGROUND

Education of undergraduates in implant dentistry has been extended. In order to assess the correct implant position, the accuracy of implant insertion using templates for pilot-drill guided and full-guided implant insertion was examined in a laboratory set-up in a cohort of undergraduates.

METHODS

After three-dimensional planning of the implant position in partially edentulous mandibular models, individual templates for the pilot-drill guided or full-guided implant insertion in the region of the first premolar were produced. A total of 108 dental implants were inserted. The results of the radiographic evaluation of the three-dimensional accuracy were statistically analyzed. Furthermore, the participants completed a questionnaire.

RESULTS

The deviation of the three-dimensional angle of the implants inserted fully guided was 2.74 ± 1.49 degrees compared to 4.59 ± 2.70 degrees for pilot-drill guided. The difference was statistically significant (p < 0.01). The returned questionnaires revealed a high interest in oral implantology and a positive evaluation of the hands-on course.

CONCLUSIONS

In this study, the undergraduates benefited from applying full-guided implant insertion considering the accuracy in this laboratory examination. However, the clinical effects are not clear as the differences are within a small range. Based on the returned questionnaires, the implementation of practical courses in the undergraduate curriculum should be encouraged.

Comparison of Static and Dynamic Navigation in Root End Resection Performed by Experienced and Inexperienced Operators: An In Vitro Study

INTRODUCTION

This study aimed to compare the effects of static navigation (SN), a dynamic navigation system (DNS), and the freehand (FH) technique in root end resection and the differences between these effects according to the level of experience of the operator.

METHODS

Maxillary models reconstructed with Mimics software (Materialise, Leuven, Belgium) were 3-dimensionally printed and divided according to the experimental technique (FH, SN, or DNS) and the operator (experienced or inexperienced). SN was designed using 3-matic Medical software (Materialise) and printed, and a surgical approach plan for DNS was established and performed using DCARER (Suzhou, China) software. The accuracy, efficiency, and safety of the resections were assayed.

RESULTS

The length, angle, volume, and depth deviations of the root end resections were significantly lower in the SN and DNS group compared with the FH group. SN significantly improved the efficiency of both operators, whereas DNS only improved the efficiency of the inexperienced operator. No difference between the SN and DNS groups was found, except for the time required for the surgery. No mishaps occurred during surgery in the SN or DNS group. The number of mishaps with the FH technique when used by the inexperienced operator was significantly higher than that registered for the rest of the groups. No interaction effect between technique and operator experience level was detected.

CONCLUSIONS

Regardless of operator experience, both SN and DNS could improve the accuracy and safety of root end resection. SN significantly improved the chairside efficiency of both operators, whereas DNS was more helpful for the inexperienced operator.

Biopsies of osseous jaw lesions using 3D-printed surgical guides: a clinical study

Background

Bone biopsies are often necessary to make a diagnosis in the case of irregular bone structures of the jaw. A 3D-printed surgical guide may be a helpful tool for enhancing the accuracy of the biopsy and for ensuring that the tissue of interest is precisely removed for examination. This study was conducted to compare the accuracy of biopsies performed with 3D-printed surgical guides to that of free-handed biopsies.

Methods

Computed tomography scans were performed on patients with bony lesions of the lower jaw. Surgical guides were planned via computer-aided design and manufactured by a 3D-printer. Biopsies were performed with the surgical guides. Bone models of the lower jaw with geometries identical to the patients’ lower jaws were produced using a 3D-printer. The jaw models were fitted into a phantom head model and free-handed biopsies were taken as controls. The accuracy of the biopsies was evaluated by comparing the parameters for the axis, angle and depth of the biopsies to the planned parameters.

Results

Eight patients were included. The mean deviation between the biopsy axes was significantly lower in guided procedures than in free-handed biopsies (1.4 mm ± 0.9 mm; 3.6 mm ± 1.0 mm; p = 0.0005). The mean biopsy angle deviation was also significantly lower in guided biopsies than in free-handed biopsies (6.8° ± 4.0; 15.4° ± 3.6; p = 0.0005). The biopsy depth showed no significant difference between the guided and the free-handed biopsies.

Conclusions

Computer-guided biopsies allow significantly higher accuracy than free-handed procedures.

Material Extrusion Based Fabrication of Surgical Implant Template and Accuracy Analysis

An implant template with great precision is significantly critical for clinical application. Currently, the application of an immediate implant remains limited by the deviations between the planned and actual achieved positions and long periods required for preparation of implant templates. Material Extrusion (MEX), as one kind of 3D printing method, is well known for its low cost and easy operation. However, the accuracy of the implant template printed by MEX has not been fully researched. To investigate the accuracy and feasibility of in vitro computer-guided surgery assisted with a MEX printed template, unidentified plaster samples missing a maxillary molar are digitalized. Mimics software (Materialise, Leuven, Belgium) is used for preoperative design. Surgical templates are fabricated by a MEX 3D printer (Lingtong III, Beijing SHINO, Beijing, China). Postoperative CBCT data are obtained after surgical template placement. The differences in positions of X, Y, Z, and dXYZ as well as angulations between the placed and the designed template are measured on labiolingual and mesiodistal planes. The deviations of the planned and the actual outcome in each dimension are observed and analyzed. Data from different samples indicate that the mean deviation of the angle measures approximately 3.640°. For position deviation, the maximum deviation is found in the z-direction and the mean deviation is about 0.365 ± 0.136 mm. The mean deviation of space Euclidean distance dXYZ is approximately 0.537 ± 0.123 mm. Implant templates fabricated by MEX present a relatively high accuracy for tooth-supported guide implantation.

Evaluation of symmetry behavior of surgically assisted rapid maxillary expansion with simulation-driven targeted bone weakening

OBJECTIVES

Surgically assisted rapid maxillary expansion (SARME) is a treatment modality to overcome maxillary constrictions. During the procedure of transverse expansion, unwanted asymmetries can occur. This retrospective study investigates the transverse expansion behavior of the maxilla utilizing a simulation-driven SARME with targeted bone weakening.

MATERIALS AND METHODS

Cone beam computer tomographies of 21 patients before (T1) and 4 months after treatment (T2) with simulation-driven SARME combined with a transpalatal distractor (TPD) and targeted bone weakening were superimposed. The movements of the left, right, and frontal segments were evaluated at the modified WALA ridge, mid root level, and at the root tip of all upper teeth. Linear and angular measurements were performed to detect dentoalveolar changes.

RESULTS

Dentoalveolar changes were unavoidable, and buccal tipping of the premolars (6.1° ± 5.0°) was significant (p < 0.05). Transverse expansion in premolar region was higher (6.13 ± 4.63mm) than that in the molar region (4.20 ± 4.64mm). Expansion of left and right segments did not differ significantly (p > 0.05).

CONCLUSION

Simulation-driven SARME with targeted bone weakening is effective to achieve symmetrical expansion in the transverse plane.

CLINICAL RELEVANCE

Simulation-driven targeted bone weakening is a novel method for SARME to achieve symmetric expansion. Dental side effects cannot be prohibited.

In-house 3D-printed surgical guides for osseous lesions of the lower jaw: an experimental study

Background

The accuracy of computer-assisted biopsies at the lower jaw was compared to the accuracy of freehand biopsies.

Methods

Patients with a bony lesion of the lower jaw with an indication for biopsy were prospectively enrolled. Two customized bone models per patient were produced using a 3D printer. The models of the lower jaw were fitted into a phantom head model to simulate operation room conditions. Biopsies for the study group were taken by means of surgical guides and freehand biopsies were performed for the control group.

Results

The deviation of the biopsy axes from the planning was significantly less when using templates. It turned out to be 1.3 ± 0.6 mm for the biopsies with a surgical guide and 3.9 ± 1.1 mm for the freehand biopsies.

Conclusions

Surgical guides allow significantly higher accuracy of biopsies. The preliminary results are promising, but clinical evaluation is necessary.

Implant insertion using an orientation template and a full-guiding template - A prospective model analysis in a cohort of dentists participating in an implantology curriculum

BACKGROUND

Dental implantology has become an established option for treating tooth loss over the recent decades. Before inserting an implant in a clinical situation, theoretical and practical training is recommended. Different methods are available to give assistance in determining the correctly planned implant position. In this study, two different guiding methods were assessed considering their accuracy for implant insertion in a group of dentists.

METHODS

After three-dimensional planning of the implant positions, two surgical templates were manufactured as follows: in region 34 a stereolithographic template was used to perform a full-guided implant insertion, in region 44 a CAD/CAM milled template was used to determine the implant position and subsequently, perform a free-hand insertion. In total, 86 implants were placed in mandibular models by 43 dentists participating in a postgraduate curriculum. The differences between planned and achieved implant positions were measured and statistically analyzed.

RESULTS

The implants inserted fully-guided showed a lower deviation of the three-dimensional angulation (2.266 ± 1.443 degrees vs. 7.954 ± 4.372 degrees) and the cumulated mismatch of the implant position (0.547 ± 0.237 mm vs. 1.160 ± 0.427 mm) compared to the free-handed mode. For the angulation and the mismatch at the implant base the differences were statistically significant (p < 0.001).

CONCLUSIONS

Within the limits of the study it can be summarized that the full-guided implant insertion leads to a higher transfer accuracy compared to the free-hand method in a cohort of dentist inexperienced in dental implantology. However, the clinical effect has to be discussed as the study was performed using artificial mandibles and ideal conditions.

Influence of 3D- printing method, resin material, and sterilization on the accuracy of virtually designed surgical implant guides

STATEMENT OF PROBLEM

Three-dimensional printing has introduced new manufacturing methods. However, information on the influence of the specific printing technology, material, sterilization, and the comparison between printing and milling on the accuracy of surgical guides is lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the influence of the manufacturing method (printing and milling), printing technology stereolithography (SLA) and digital light processing (DLP), material, and sterilization on the accuracy of digitally designed surgical implant guides.

MATERIAL AND METHODS

Resin patient replicas with a single edentulous space were used to place 132 implants with digitally designed surgical guides. The accuracy of postoperative implant position was analyzed for the manufacturing method (printing and milling), resin materials, and preoperative autoclaving. To determine 3D accuracy, angular displacement, mean horizontal crestal, apical displacement, and the linear vertical displacement at the apex were calculated separately for each group (n=12). In addition, the surgical guides were qualitatively analyzed by using field emission scanning electron micrograph.

RESULTS

The postoperative angular deviation ranged from 0.76 ±0.52 degrees (Rapidshape D20II with NextDent SG) to 2.43 ±0.64 degrees (Form2 with NextDent SG) (P<.001). Linear horizontal displacement at the crest was smallest for Rapidshape D20II with 3Delta Guide (0.27 ±0.08 mm) and highest for Form2 with NextDent SG (0.54 ±0.10 mm) (P<.001). Linear horizontal displacement at the apex ranged from 0.36 ±0.10 mm (SolFlex 350 with V-Print SG) to 0.89 ±0.32 mm (Form2 with NextDent SG) (P<.001). Considering the vertical position displacement was no more than 0.43 ±0.07 mm (Form2 with NextDent SG) short of the apex, none of the implant tips were displaced apically. Preoperative autoclaving differentially impaired the accuracy of surgical guides.

CONCLUSIONS

The specific manufacturing technique, the 3D printing device, the resin material, and the application of preoperative sterilization all affected the accuracy of the postoperative implant position. Irrespective of the manufacturing method, all implants were placed within the commonly accepted safety distance.

The Digital Abutment Check: An Improvement of the Fully Digital Workflow

By using modern digitalization techniques, an existing denture can be digitized and aid the provision of a new implant-supported denture according to a fully digital workflow. This includes fully navigated implant surgery and results in an immediately provided prosthetic restoration. However, even with the current digital workflow, it is challenging to achieve a definitive prosthetic restoration in a single treatment session. In order to achieve a definitive denture in as few treatment sessions as possible, we have implemented the digital abutment test. This test modified the existing data set and determined the final restoration. In the present case, the preexisting maxillary removable complete denture was converted into a fixed immediate restoration using the fully digital workflow. The workflow is divided into two treatment phases, each with three treatment sessions, where part of the second phase involves an innovative digital abutment check. The illustrated case shows an effective use of current digital possibilities. Special attention was also paid to a minimally invasive course of therapy.

Alveolar ridge preservation and primary stability as influencing factors on the transfer accuracy of static guided implant placement: a prospective clinical trial

Background

The aim of this prospective clinical study was to investigate differences between virtually planned and clinically achieved implant positions in completely template-guided implant placements as a function of the tooth area, the use of alveolar ridge preservation, the implant length and diameter, and the primary implant stability.

Methods

The accuracy of 48 implants was analyzed. The implants were placed in a completely template-guided manner. The data of the planned implant positions were superimposed on the actual clinical implant positions, followed by measurements of the 3D deviations in terms of the coronal (dc) and apical distance (da), height (h), angulation (ang), and statistical analysis.

Results

The mean dc was 0.7 mm (SD: 0.3), the mean da was 1.4 mm (SD: 0.6), the mean h was 0.3 mm (SD: 0.3), and the mean ang was 4.1° (SD: 2.1). The tooth area and the use of alveolar ridge preservation had no significant effect on the results in terms of the implant positions. The implant length had a significant influence on da (p = 0.02). The implant diameter had a significant influence on ang (p = 0.04), and the primary stability had a significant influence on h (p = 0.02).

Conclusion

Template-guided implant placement offers a high degree of accuracy independent of the tooth area, the use of measures for alveolar ridge preservation or the implant configuration.

A clinical benefit is therefore present, especially from a prosthetic point of view.

Trial registration

German Clinical Trial Register and the International Clinical Trials Registry Platform of the WHO: DRKS00005978; date of registration: 11/09/2015.

Advantages and limitations of implant surgery with CAD/CAM surgical guides: A literature review

Background

The purpose of this study is to review the available literature associated with implant surgery using computer-aided design/computer-aided manufacturing (CAD/CAM) surgical guides and discuss the advantages and disadvantages of this advanced technique.

Material and Methods

An electronic literature search was conducted in the PubMed database for the relevant information on implant placement with CAD/CAM surgical guides. This review was constructed following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Articles were limited to those published within the past 10 years and in the English language. Only clinical studies were included. Inclusion criteria were: studies including 10 implants or more and studies presenting angular deviations in degrees and linear deviations in millimeter. Observational studies, reviews, animal studies, in vitro studies, case reports, simulation studies were excluded. Nine articles were included for qualitative synthesis.

Results

The initial search detected 61 articles, and after screening abstracts, a total of 15 articles were selected for full-text review. After the full-text analysis of the 15 articles, six articles were excluded as they did not meet inclusion criteria for study design, study population, and implant placement with data presentation for angular and linear deviations. Ultimately, nine articles providing angular and linear deviations between planned and actual placed implants were used in this review. Common problems that may be encountered by clinicians were listed, and recommendations were made on how to avoid those problems.

Conclusions

It has been suggested that although unrealistic expectations are often associated with implant placement with CAD/CAM surgical guides, there is no impeccable accuracy in the clinic. This review demonstrated that the practitioners should be aware of the angular and linear deviations up to 5 ° and 2.3 mm. Therefore, inexperienced dentists should obtain adequate training and be familiar with the basic steps with CAD/CAM surgical guides to avoid complications.

Key words:CAD/CAM, CBCT, implant, stereolithography, surgical guide.

[Research advances in the use of digital surgical guides in implantology]

Dental implants have become the main choice for patients to fill in their missing teeth. A precise placement is the basis for a functional and aesthetic restoration. A digital surgical guide is a carrier that transfers the preoperative plan of dental implants to the actual surgery. This paper provides some references that can help clinicians improve the accuracy of implant surgery by stating the development, classification, advantages and disadvantages, and factors that affect the accuracy of digital guides.

Guided implant surgery risks and their prevention

Ideal implant placement may reduce surgical complications, such as nerve injury and lingual cortical plate perforation, and minimize the likelihood of functional and prosthetic compromises. Guided implant surgery (GIS) has been used as the means to achieve ideal implant placement. GIS refers to the process of digital planning, custom-guide fabrication, and implant placement using the custom guide and an implant system-specific guided surgery kit. GIS includes numerous additional steps beyond the initial prosthetic diagnosis, treatment planning, and fabrication of surgical guide. Substantial errors can occur at each of these individual steps and can accumulate, significantly impacting the final accuracy of the process with potentially disastrous deviations from proper implant placement. Pertinent overall strategies to reduce or eliminate these risks can be summarized as follows: complete understanding of the possible risks is fundamental; knowledge of the systems and tools used is essential; consistent verification of both diagnostic and surgical procedures after each step is crucial; proper training and surgical experience are critical. This review article summarizes information on the accuracy and efficacy of GIS, provides insight on the potential risks and problems associated with each procedural step, and offers clinically relevant recommendations to minimize or eliminate these risks.

An Easy Approach for the Fabrication of Surgical Template for Placement of Mini-implant

The success of dental implant depends on meticulous treatment planning. Restorative problems are often common with improper placement of implants, especially where the alveolar bone quantity is compromised. The accuracy needed in placement of the mini-implant is even more. Hence, the use of a surgical guide becomes essential. Various authors have suggested techniques for the fabrication of surgical and radiographic stents. These techniques make use of different materials in fabrication of stent. This article presents a simple technique for the fabrication of a surgical guide for the placement of mini-implants using simple readily available materials. The technique can be modified to be used for regular diameter implants.

An update on applications of 3D printing technologies used for processing polymers used in implant dentistry

Polymer additive manufacturing (AM) technologies have been incorporated in digital workflows within implant dentistry. This article reviews the main polymer AM technologies in implant dentistry, as well as their applications in the field such as manufacturing surgical guides, custom trays, working implant casts, and provisional restorations.

Pilot-drill guided vs. full-guided implant insertion in artificial mandibles-a prospective laboratory study in fifth-year dental students

Background

As a growing field in dentistry, the practical education during the undergraduate curriculum in implant dentistry should be extended. Not only the theoretical background but also practical skills are crucial to place implants in patients. In order to determine the exact implant position, several positioning aids are available. In the present laboratory study, the accuracy of implant insertion using two different guiding modes in a group of inexperienced participants was assessed.

Methods

After three-dimensional planning using the data of a cone beam computed tomography of artificial mandibles, surgical templates were manufactured by thermoforming. In region 35, a sleeve for the pilot drill was used, whereas in region 45, a sleeve allowing a full-guided implant insertion was inserted. Subsequently, a total of 104 implants were placed by 52 undergraduates. Radiographical assessment of the three-dimensional accuracy was performed. Furthermore, the time required to insert the implants was recorded. Statistical analysis followed.

Discussion

When comparing the three-dimensional accuracy of the virtually planned to the actual inserted implant, a statistically significantly higher accuracy in three-dimensional angulation was achieved for the full-guided (3.388 ± 1.647°) compared to the pilot-drill guided mode (5.792 ± 3.290°). Furthermore, the time required to insert the implant was shorter for the full-guided template (6.23 ± 1.78 min) vs. for the pilot-drill guided (8.84 ± 2.39 min). Both differences reached a statistical significance (p < 0.001).

Conclusion

Within the limit of this laboratory study, the results suggest that inexperienced surgeons benefit from a full-guided implant insertion. However, the clinical effects have to be discussed as the mismatch was varying in the decimillimeter range.

Impact of voxel size and scan time on the accuracy of three-dimensional radiological imaging data from cone-beam computed tomography

PURPOSE

Three-dimensional (3D) radiological imaging plays an important role in surgical planning used in modern dentistry. The aim of this study was to optimize imaging parameters with a special focus on voxel size and scan time.

MATERIAL AND METHODS

A virtual 3D master model of a macerated human skull was generated using an industrial optical noncontact white light scanner. The skull was X-rayed with cone-beam computed tomography that was applied using different settings for voxel size and acquisition time (voxel edge length of 0.3 mm, scan times 4.8 s and 8.9 s; voxel edge length of 0.2 mm, scan times 14.7 s and 26.9 s). The scan was repeated 10 times at each setting. The CBCT scans were converted into 3D virtual models (actual value), which were superimposed with the 3D master model (reference value) to detect absolute differences.

RESULTS

The mean value of deviation increased with increasing voxel size and decreasing scan time. For a voxel edge length of 0.3 mm, the mean values of deviation were 0.33 mm and 0.22 mm with scan times of 4.8 s and 8.9 s, respectively. For a voxel edge length of 0.2 mm, the mean deviations were 0.16 mm and 0.14 mm with scan times of 14.7 s and 26.9 s, respectively.

CONCLUSIONS

When using small voxel sizes, the scan time does not have a significant impact on image accuracy and therefore the scan time can be shortened. However, for larger voxel sizes, shorter scan times can lead to increased inaccuracy.

Objects build orientation, positioning, and curing influence dimensional accuracy and flexural properties of stereolithographically printed resin

OBJECTIVE

To evaluate the influence of printing parameters on flexural properties and accuracy of SLA-printed standard objects.

METHODS

Thirty specimens were printed in 0°, 45° and 90° orientation. Fourth nine more specimens were printed evenly on the build platform. forty more specimens were printed and polymerized with three curing unit. Length, height and width was measured three times for each specimen and compared to the original dimensions. Afterwards all specimens underwent a three-point-bending test to assess their flexural properties. One way ANOVA and the Post-Hoc all pairs Tukey-Kramer HSD test were used for data evaluation.

RESULTS

The print orientation influences the printing accuracy. The parameters printed along the Z-axis are particularly prone to inaccuracies. Specimens with 45° orientation were found to be the most accurate. Object printed on the borders of build platform a rather prone to inaccuracies than those in the center. The 90° specimens with layer orientation parallel to the axial load showed the superior flexural strength and flexural modulus. The use of different curing unit is unlikely to affect the objects printing accuracy and flexural properties.

SIGNIFICANCE

The anisotropical behavior of printed specimens with regards to build orientation and positioning was revealed. The understanding of how the adjustable printing parameter influence the printing outcome is important for a precise fabrication of surgical guides. Inaccuracies up to 10% along the Z-axis, as revealed in the present study,may restrict an accurate implant placement.

The Use of Orientation Templates and Free-Hand Implant Insertion in Artificial Mandibles-An Experimental Laboratory Examination in Fifth-Year Dental Students

Implant dentistry is a growing field in the education of undergraduate dental students. The present laboratory study evaluates factors which may potentially influence the accuracy of free-hand implant insertion and the use of an orientation template. After three-dimensional planning using coDiagnostiX^TM, orientation templates, including sleeves for the pilot-drill in regions 41 and 45, were manufactured by thermoforming. Sixty-one fifth year dental students inserted one implant using the orientation template and another implant free-hand in an artificial mandible. Information regarding age, sex, handedness, education, and the time required for implant insertion were recorded. Subsequently, the mandibles were scanned using cone-beam-computed tomography and the accuracy of the implant position was assessed, while statistical analysis followed. The free-hand implant insertion resulted in a distal deviation of −1.34 ± 5.15° and a mesial mismatch of 0.06 ± 0.79 mm at the artificial bone level compared to the sleeves. When using the orientation templates, the deviation decreased to −0.67 ± 3.48° and a distal mismatch of −0.22 ± 0.62 mm was achieved. The difference was statistically significant for the mismatch (p < 0.049). Regarding the limitations of our study, it could be said that the accuracy level achieved by dental undergraduates using implant placement with orientation templates is comparable to that in other studies.

Evaluation of volumetric dimensional changes in posterior extraction sites with and without ARP using a novel imaging device

BACKGROUND

Alveolar ridge volume loss may be minimized when postextraction sockets are filled by bone substitutes.

PURPOSE

The aim of the study was to measure the effect of alveolar ridge preservation (ARP) in maintaining the external contour of the ridge after fresh socket grafting with or without particulate anorganic bovine bone mineral (BBM) and resorbable barrier covering.

MATERIALS AND METHODS

In the present controlled study, patients subjected to single-tooth extraction were allocated to 2 groups: postextraction sockets grafted with bovine bone mineral (bbm), and naturally healing sockets (nat). Before and at 5 months following tooth extraction, plaster cast contours of the sockets were acquired by means of an optical scanner; the 2 contours of each patient underwent voxelization and fusion using a matrix elaborator. Outcome variables at 5 months (volumetric, surface, and linear changes) were measured in digital fused plaster casts with a dental scan software analyzing a volume of interest ranging from residual papilla to 10 mm toward the apical point. Intra- and inter-group pair-wise variables' comparisons were conducted. Level of significance was set at 0.05.

RESULTS

Twenty-four sites were enrolled: 12 ARP and 12 naturally healed. Five-month percentage of volume loss of the bbm-group (21.7% ± 7.4%) was significantly lower (Ps < .0003) than that of the naturally healing group (38.8% ± 7.9%). When tooth position was investigated, volume loss in percentage registered a significantly better (P values ≤ .0485) behavior in molars (ΔV% = -19.1% ± 6.5% and ΔV% = -35.6% ± 7.6%, respectively, for bbm and nat) than that in premolars (ΔV% = -26.9% ± 7.2% and ΔV% = -45.1% ± 4.2%, respectively, for bbm and nat), in both the preserved and naturally healing groups.

CONCLUSION

The dimensional loss in postextraction sockets grafted with anorganic bovine bone substitute and covered by a resorbable collagen barrier was lower than that of the naturally healing sites. However, ridge preservation was able to maintain almost 80% of the pristine bone.